There are some products, having generally the same size as that of a semiconductor chip, in a semiconductor device formed by shielding the semiconductor chip with resin. In such a semiconductor device, a surface of the semiconductor chip on which electrode terminals are formed is shielded and external connection terminals are arranged thereon for connecting the chip to a circuit board so that the resultant device has the same size as that of the semiconductor chip (chip scale).
FIG. 14 shows a sectional view of a prior art semiconductor device having a chip size, in which the connection between a lead 34 and an electrode terminal 12 of a semiconductor chip 10 and the support for an external connection terminal (solder ball) 40 are illustrated. This semiconductor device is structured as follows:
An insulating member 20 is adhered onto a surface 10a of the semiconductor chip 10 on which the electrode terminal 12 is formed, without covering the electrode terminal 12. The insulating member 20 has a main layer of elastomer 22 and is adhered to the semiconductor 10 via an adhesive 24. A circuit pattern 30 has a land 32 at one end for the connection to the external connection terminal, and a lead 34 which is a conductive layer at the other end. The circuit pattern 30 is supported by an insulating film 36 which constitutes, together with the circuit pattern 30, a tape substrate 38. The tape substrate 38 is adhered to the insulating member 20 in the land 32 and connected to the electrode terminal 12 in the lead 34 by a bonding.
After the lead 34 is bonded, an exposed portion of the lead 34 and the electrode terminal 12 is shielded with resin 90. The circuit pattern 30 is adhered to the insulating film 36 by an adhesive 35. The external connection terminal is a solder ball 40 or the like and is connected to the land 32.
To constitute the above-mentioned lamination, first, the tape substrate 38 is formed, to which the elastomer 22 carrying the adhesive layer 24 is then adhered. With such an adhesive layer 24 the semiconductor chip 10 is adhered (see FIG. 2 in which a production method is illustrated).
FIG. 15 shows the bonding of the lead 34 to the electrode terminal 12. When the lead 34 is bonded, as illustrated, a bonding tool 91 comes into contact with a top surface of the lead 34 and pricks the lead 34 supported by the insulating film 36, while pushing the lead 34 by a front end of the bonding tool 91. The lead 34 is bent thereby to be in contact with the electrode terminal 12 and is bonded thereto. According to this bonding operation, the lead 34 is curved from the tape substrate 38 toward the electrode terminal 12 as illustrated. The bonding operation of the bonding tool 91 is a hot-press bonding while using ultrasound or another method.
FIG. 16 is an enlarged perspective view of the semiconductor chip 10 on which the tape substrate 38 is arranged. The lead 34 is supported to bridge over a window 36a provided in the insulating film 36. The tape substrate 38 is positioned so that the electrode terminal 12 of the semiconductor chip 10 is exposed in correspondence to the window 36a and the lead 34 is located above the respective electrode terminal 12. After the bonding tool 91 is pushed down from a position above a cutting point of the lead 34 and cuts the lead 34, the bonding tool 91 slides from the cutting point down to the electrode 12 (bonding point) to bond the lead 34 to the electrode terminal 12. The bonding operation is carried out by the bonding tool 91, one by one, on all the leads 34 as illustrated.
In the prior art, after the lead 34 is bonded as described above, a resin is coated along the outer edge of the semiconductor chip 10 through a dispenser to shield the exposed portions of the lead 34 and the electrode terminal 12.
However, in this prior art, it is difficult to properly coat the shield resin since the width of the area to be shielded is small. Further, to obtain a favorable finish, it is necessary to carry out the shielding operation at a lower speed to avoid dropping the resin, which results in a deterioration in productivity.
If the resin is not sufficiently coated, a cut end 34a or a shoulder 34b of the lead 34 may be exposed to lower the reliability of the resultant semiconductor device.
On the other hand, if the shield resin is excessively applied, the outer dimensions of the product become improper for the handling in the subsequent process.
Also, since a corner 10c of the semiconductor chip 10 is exposed and liable to chip off (chipping), the handling thereof is difficult.